It is known that the Natufian people used sickles to cut and harvest wild grains in the Mediterranean region as early as 12,500 B.c. But did this practice lead to domesticated grains? Wild grains are brittle (easily broken) and the seeds burst forth when ripe, whereas nonbrittle “domesticated” grains remain on the plant until beaten off. In wild grains, there are one or two nonbrittle mutants to every 2 to 4 million brittle individuals. If ripe grain is cut with a sickle and taken to a village to dry and be beaten out, a higher percentage of the nonbrittle mutants is harvested since many of the brittle seeds are lost. If this grain is then planted, this ratio will increase each harvest
Gordon Hillman, an archaeologist, and Stuart Davies, a biologist from the University of Wales, have used their knowledge of plant genetics and ancient gathering techniques-much of it acquired by experimentation-to estimate how long the change from wild to domestic strains would take. By using computer simulation they showed that in ideal circumstances as little as twenty cycles of harvesting and replanting in new patches could have transformed a wild, brittle type of wheat into the domesticated nonbrittle variant. Under more realistic conditions, 200 to 250 years is the most likely period of transition.
The archaeological evidence makes it clear that this transition did not happen during the Natufian Period (about 12,500 to 10,200 years ago). There are microscopic differences between the shape of the grain from domestic cereals and wild varieties, and although cereal grains are rare in the Natufian archaeological record, all of those known are clearly from wild cereals. Not for another millennium at least do we encounter the first domesticated grains-from the settlements of Abu Hureyra and Tell Aswad in Syria and Jericho in Palestine. So the Natufian people appear to have cut the wild cereal stands with their sickles for as much as 3,000 years without the evolutionary leap from brittle to nonbrittle plants.
There seems to be a very simple explanation for this, identified in some remarkable research by Romana Unger-Hamilton during the 1980s while she worked at the Institute of Archaeology in London. Under the guidance of Gordon Hillman she spent many months replicating the Natufian style of harvesting wild cereals. Using identical sickles made with bone handles and flint blades, she cut stands of wild wheat and barley on the slopes of Mount Carmel, around the Sea of Galilee and in southern Turkey in a series of controlled experiments. The blades were then microscopically examined for signs of “sickle-gloss” (traces of wear which cause a blade to shine)-the texture, location, and intensity of gloss will vary with different types of cereals and at different stages of ripeness.
Unger-Hamilton found that the sickle-gloss on the true Natufian blades was most similar to that on the blades she used to harvest cereals that were not yet ripe. In that state, the brittle plants would have shed only a little of their grain, so that it would be collected from the nonbrittle variants in virtually the same minute proportion as from those plants within the stand. So even if the Natufian people were planting seed to generate new stands of wild cereals, nonbrittle variants were unable to become dominant. Harvesting the unripe ears was perfectly sensible as it avoided the loss of most of the grain from the brittle plants, which would have already been shed to the ground.
Another factor probably prevented the emergence of domesticated cereals among the Natufians: their sedentary lifestyle. Patricia Anderson, of the Jales Research Institute in Paris, undertook a similar program of research to that of Romana Unger-Hamilton and confirmed many of her results. She also found that when wild stands are cut with sickles, even when still in a green stage, the grain that falls to the ground is quite sufficient to provide for the next year’s crop. So the Natufians would have only needed to plant if they were beginning a brand-new plot of cereals-otherwise they could have relied upon growback at the existing stands. Even if the grain collected by the Natufian people did have a higher proportion of the nonbrittle variants, unless they were creating new plots of cereals in new places, these variants would never have had the opportunity to become the dominant form.
题目：
1
It is known that the Natufian people used sickles to cut and harvest wild grains in the Mediterranean region as early as 12,500 B.c. But did this practice lead to domesticated grains? Wild grains are brittle (easily broken) and the seeds burst forth when ripe, whereas nonbrittle “domesticated” grains remain on the plant until beaten off. In wild grains, there are one or two nonbrittle mutants to every 2 to 4 million brittle individuals. If ripe grain is cut with a sickle and taken to a village to dry and be beaten out, a higher percentage of the nonbrittle mutants is harvested since many of the brittle seeds are lost. If this grain is then planted, this ratio will increase each harvest
According to paragraph 1, the main difference between wild and domesticated cereals is
Ahow big the grains are when ripe
Bwhether the grains stay on unless beaten off
Chow much grain is produced on each plant
Dhow quickly the grains ripen
2
Gordon Hillman, an archaeologist, and Stuart Davies, a biologist from the University of Wales, have used their knowledge of plant genetics and ancient gathering techniques-much of it acquired by experimentation-to estimate how long the change from wild to domestic strains would take. By using computer simulation they showed that in ideal circumstances as little as twenty cycles of harvesting and replanting in new patches could have transformed a wild, brittle type of wheat into the domesticated nonbrittle variant. Under more realistic conditions, 200 to 250 years is the most likely period of transition.
Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
AAn archaeologist and a biologist have used their combined knowledge to estimate how long the change from wild to domestic strains would take
BGordon Hillman and Stuart Davies conducted experiments on wild and domesticated strains, from which they acquired knowledge and techniques for the study of plant genetics.
CEstimating how long it took to develop domestic strains helped archaeologists and biologists acquire knowledge of plant genetics and ancient gathering techniques.
DDrawing on plant genetics and ancient gathering techniques, scientists have designed an experiment to recreate wild strains from domesticated strains.
3
The archaeological evidence makes it clear that this transition did not happen during the Natufian Period (about 12,500 to 10,200 years ago). There are microscopic differences between the shape of the grain from domestic cereals and wild varieties, and although cereal grains are rare in the Natufian archaeological record, all of those known are clearly from wild cereals. Not for another millennium at least do we encounter the first domesticated grains-from the settlements of Abu Hureyra and Tell Aswad in Syria and Jericho in Palestine. So the Natufian people appear to have cut the wild cereal stands with their sickles for as much as 3,000 years without the evolutionary leap from brittle to nonbrittle plants.
In paragraph 3, why does the author provide information about the differences in shape between the grains of domestic cereals and the grains of wild varieties?
ATo emphasize how minor the differences between wild and domestic cereals are
BTo account for the scarcity of grains in the Natufian archaeological record
CTo support the argument that domestication occurred very gradually
DTo explain how archaeologists determined that domestication did not occur at the time of the Natufians
4
There seems to be a very simple explanation for this, identified in some remarkable research by Romana Unger-Hamilton during the 1980s while she worked at the Institute of Archaeology in London. Under the guidance of Gordon Hillman she spent many months replicating the Natufian style of harvesting wild cereals. Using identical sickles made with bone handles and flint blades, she cut stands of wild wheat and barley on the slopes of Mount Carmel, around the Sea of Galilee and in southern Turkey in a series of controlled experiments. The blades were then microscopically examined for signs of “sickle-gloss” (traces of wear which cause a blade to shine)-the texture, location, and intensity of gloss will vary with different types of cereals and at different stages of ripeness.
The word “series” in the passage is closest in meaning to
Aselection
Bsequence
Cvariety
Dcombination
5
There seems to be a very simple explanation for this, identified in some remarkable research by Romana Unger-Hamilton during the 1980s while she worked at the Institute of Archaeology in London. Under the guidance of Gordon Hillman she spent many months replicating the Natufian style of harvesting wild cereals. Using identical sickles made with bone handles and flint blades, she cut stands of wild wheat and barley on the slopes of Mount Carmel, around the Sea of Galilee and in southern Turkey in a series of controlled experiments. The blades were then microscopically examined for signs of “sickle-gloss” (traces of wear which cause a blade to shine)-the texture, location, and intensity of gloss will vary with different types of cereals and at different stages of ripeness.
The word “traces” in the passage is closest in meaning to
Arecent discoveries
Bresults
Cexamples
Dsmall amounts
6
There seems to be a very simple explanation for this, identified in some remarkable research by Romana Unger-Hamilton during the 1980s while she worked at the Institute of Archaeology in London. Under the guidance of Gordon Hillman she spent many months replicating the Natufian style of harvesting wild cereals. Using identical sickles made with bone handles and flint blades, she cut stands of wild wheat and barley on the slopes of Mount Carmel, around the Sea of Galilee and in southern Turkey in a series of controlled experiments. The blades were then microscopically examined for signs of “sickle-gloss” (traces of wear which cause a blade to shine)-the texture, location, and intensity of gloss will vary with different types of cereals and at different stages of ripeness.
According to paragraph 4, Romana Unger-Hamilton did all of the following as part of her research EXCEPT
Aconduct experiments at sites on Mount Carmel, the Sea of Galilee, and southern Turkey
Bexperiment with various sickles made of different materials
Cuse sickles that resembled those of Natufians to cut wheat and barley
Dexamine the patterns of wear on the sickles with a microscope
7
Unger-Hamilton found that the sickle-gloss on the true Natufian blades was most similar to that on the blades she used to harvest cereals that were not yet ripe. In that state, the brittle plants would have shed only a little of their grain, so that it would be collected from the nonbrittle variants in virtually the same minute proportion as from those plants within the stand. So even if the Natufian people were planting seed to generate new stands of wild cereals, nonbrittle variants were unable to become dominant. Harvesting the unripe ears was perfectly sensible as it avoided the loss of most of the grain from the brittle plants, which would have already been shed to the ground.
According to paragraph 5, harvesting grain before it was ripe resulted in
Amarks unlike those found on actual Natufian blades
Ban increase in the proportion of nonbrittle variants in the population
Cless success in generating new stands of wild cereals
Dless loss of grain during the harvesting process
8
Another factor probably prevented the emergence of domesticated cereals among the Natufians: their sedentary lifestyle. Patricia Anderson, of the Jales Research Institute in Paris, undertook a similar program of research to that of Romana Unger-Hamilton and confirmed many of her results. She also found that when wild stands are cut with sickles, even when still in a green stage, the grain that falls to the ground is quite sufficient to provide for the next year’s crop. So the Natufians would have only needed to plant if they were beginning a brand-new plot of cereals-otherwise they could have relied upon growback at the existing stands. Even if the grain collected by the Natufian people did have a higher proportion of the nonbrittle variants, unless they were creating new plots of cereals in new places, these variants would never have had the opportunity to become the dominant form.
Which of the following can be inferred from paragraph 6 about the grain Natufian people collected?
ANatufians depended mostly on collecting brittle variants that were produced by existing stands rather than on nonbrittle variants.
BNatufians preferred collecting nonbrittle variants and did so whenever they could
CNatufians preferred to collect grains that had fallen to the ground than to harvest grain with a sickle.
DNatufians collected grains from newly-planted plots before collecting the growback from existing stands.
